From: Lucas Braesch <lucas.braesch@gmail.com>
Date: Mon, 9 Dec 2013 10:14:14 +0000 (+0800)
Subject: Update History and Counter move on TT hit
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=86347100a5c1113e9306d63a16cde2866839373b

Update History and Counter move on TT hit

We already update killers so it is natural to extend to
history and counter move too.

Passed both short TC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 52690 W: 9955 L: 9712 D: 33023

And long TC
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 5555 W: 935 L: 808 D: 3812

bench: 7876473
---

diff --git a/src/search.cpp b/src/search.cpp
index a739b049..5205126a 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -569,6 +569,7 @@ namespace {
         TT.refresh(tte);
         ss->currentMove = ttMove; // Can be MOVE_NONE
 
+        // Update killers, history, and counter move on TT hit
         if (    ttValue >= beta
             &&  ttMove
             && !pos.capture_or_promotion(ttMove)
@@ -576,6 +577,15 @@ namespace {
         {
             ss->killers[1] = ss->killers[0];
             ss->killers[0] = ttMove;
+
+            Value bonus = Value(int(depth) * int(depth));
+            History.update(pos.moved_piece(ttMove), to_sq(ttMove), bonus);
+
+            if (is_ok((ss-1)->currentMove))
+            {
+                Square prevMoveSq = to_sq((ss-1)->currentMove);
+                Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, ttMove);
+            }
         }
         return ttValue;
     }